Getter structure



Patented Mar. 2, 1948 GETTER STRUCTURE Aden J. King, Syracuse, N. Y.,assignor tmKing q Laboratories Inc., Syracuse, N. Y., a corporav p tion 'of New York No Drawing. Application January 5, 1945, Serial No. 571,537

3 Claims. (01. 250-275) This invention relates to a getter or getter structure employed for removing residual traces of gas from vacuum tubes after the same have been vacuumized mechanically.

At the present time, the extremely high vacuum necessary to be obtained in vacuum tubes, such as are customarily used in electronic work, is obtained by volatilizing, within the hermetically sealed tube, a clean-up agent or getter by the application of heat at high temperature, this application being commonly known as flashing.

The clean-up agent commonly used consists of one or more of the alkaline earth metals, such as barium, this being alloyed with aluminum, or other metals, and the mixture being arranged in a small depression formed in a thin sheet metal support. These supports are usually formed of nickel or iron.

The getter structure or assembly is heated by means of a high frequency coil placed around the tube, or by so connecting the getter assembly to a suitable source of current that it is heated as a result of its resistance to the flow of current in order to raise the getter structure to the flashing temperature. In volume production of such tubes, the application of heat raises the structure to a relatively high temperature. During the vaporizing or flashing of the getter material, the temperature is often suflicient to cause the components of the getter material to alloy with the metal support. Usually the alkaline earth metal is mixed or alloyed with aluminum and under sufficiently high temperature, the aluminum will form a low melting alloy with the metal support which may cause a perforation of the support and thus permit the vapor of the getter material to flow in directions not desired as, for example, to be deposited upon the operating elements of the tube, thereby rendering the vacuum tube useless.

It is the object of this invention to provide a getter structure wherein the aluminum associated with the clean-up material will not alloy with the metal support, or at least to reduce this tendency to a minimum.

The invention is carried out by providing a metal support in or on which a quantity of getter material is positioned, the material consisting of a metal, usually aluminum, alloyed or mixed with a clean-up material, such as barium, and including an intimate mixture of an oxide of the metal of which the support is formed. For example, if the support is formed of iron, the getter material may consist of a powdered alloy of barium and aluminum, to which is added iron oxide. This material is conveniently made up in the form of a powdered mixture, a small quantity of which is compressed into a depression formed in the support.

If the support is formed of nickel, nickel oxide is added to the getter material instead of the iron oxide. A getter material of this nature which I have found to give excellent results consists of 100 parts by weight of the powdered getter alloy, and 15 to 40 parts by weight of nickel oxide. The getter alloy, in this instance, may consist of 25% to barium and 75% to 25% aluminum, 2% to 10% of magnesium, or calcium may be added to improve the flashing qualities of the getter material. During the flashing of this material, the aluminum combines with the oxide of the nickel forming aluminum oxide. Thus, the aluminum becomes tied up with the oxygen of the nickel oxide insteadrof alloying with the nickel in the getter support to form an aluminum nickel alloy having a relatively low melting point, thereby avoiding or minimizing any possibility of aluminum alloying with the support and causing the same to be perforated.

Where the getter material support is formed of sheet iron and the iron oxide is added to the getter material, the reaction is the same. That is, the aluminum combines with the oxygen of the iron oxide forming aluminum oxide, rather than alloying with the iron of the support.

In either event, I am of the opinion that some gain may be realized by the use of my getter material in the direction of lowering the flashing temperature due to the extra heat liberated by the chemical reactions. I

What I claim is:

1. A getter structure comprising a supp "t formed of thin sheet nickel, a quantity of gett r material positioned on said support, said material comprising a mixture of Parts by weight Powdered alloy (25 to 75 %"barium, 75 to 25% aluminum) An oxide of nickel 15 to 40 2. A getter structure comprising a support formed of thin sheet nickel, a quantity of getter material positioned on said support, said material consisting of a mixture comprising Parts by weight Powdered alloy (25 to 75% barium, 75 to 25% aluminum, 2 to 10% magnesium) 100 An oxide of nickel....... 15 to 40 meme? .3. A getter structure comprising a support UNITED STATES PATENTS formed of thin sheet nickel, a quantity of getter material positioned on said support, said. mateg gg g ggs: rial 'consisting of a, mixture comprising y 2,029,144 Wiegand Jan. 28, 1936 Parts by Weight 5 2,067,817 Beggs Jan. 12, 1937 Powdered alloy (-2510 75% barium,e'75:to 7 2 100146 Miller et .a1.v N0v. 30, 1937 25% ealuminum, 2%to. 10% calcium)... 4.100 354,131 'Lederer. Apr. 11, 1939 An oxide of nickel 15 to 40 ADEN J. KING. 1m FOREIGN PATENTS Number Country Date REFERENCES CITED 3607;696 France Apr. 3, 1926 The following referenceseare xifirecordzinitlfe file of this patent: 

